Motor-control system



C. H. HODGKINS.

MOTOR CONTROL SYSTEM.

APPLICATION man SEPT. m, 1911. RENEWED m1. 5.1921.

1,406,383. Patented Feb. 14, 1922.

2 SNEETFSHEET 1.

2 ah I 5 I] A /Z r wnmzsszs: INVENTOR 2% @fllx M ytfiarks/i/Mykim C. H. HODGKINS.

MOTOR CONTROL SYSTEM. APPLICATiON FlLED SEPT.10,1917- RENEWED JAN. 5. 1921.

1 ,406,383, Patented Feb. 14, 1922.

2SHEETS-SHEET 2.

WITNESSES: INVENTOR Q Q W (mm/z wa /m UNITED STATES PATENT 'OFFICE..

CHARLES H. HODGKINS, or PITTSBURGH, PENNSYLVAN1A, ASSIGNOR TO WESTING- HOUSE ELECTRIC a n'ANUrAc'rURINe COMPANY, A CORPORATION OF PENNSYL- VANIA.

MOTOR-CONTROL SYSTEM.

Specification of Letters Patent. Patent d F b 14 1922 Application filed September 10, 1917, Serial No. 190,424. Renewed January 5, 1921. Serial No. 435,251.

To all whom it may concerns Be it known that I, CHARLns H. Hone- KINS, a subject of the King of Great Britain, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Motor-Control Systems, of which the following is a specification.

My invention relates to motor-control systems and it has particular relation to startin devices for electric motors.

My invention has for one of its objects to provide a simple combination to operate in a single 'direction" to effect the acceleration of electric motors and then to return to its initial position.

A second object of my invention is to provide means whereby the speed of a pilot motor for operating a controller may be controlled automatically in accordance with operating conditions.

In a starting apparatus constructed in accordance with my invention, apilot motor actuates a drum controller continuously in a single direction to effect the shunting of a starting resistor and then to return to its initial position. The running position of the controller coincides with the initial or off position. The pilot motor operates automatically to actuate the controller through the cycle described above, independently of the operation f the main motor which it controls.

In one form of my invention, the circuits of the pilot motor are so arranged that the controller is actuated at a. relatively slow speed when the main motor is being accelerated and at a relatively high speed when the pilot motor is operating and the circuit of the main motor is open. Moreover, means is provided for preventing the operation of the controller and the pilot motor when the main motor is accelerated and operating under normal conditions.

In the accompanying drawings, Fig. 1 is a diagrammatic view of circuits and apparatus embodying my invention. 2 is a view, similar to Fig. 1, of a modification. Fig. 3 is a schematic arrangement of the principal circuits of the systems of Figs. 1 and 2.

Referring particularly to Fig. 1, line conductors 1 and 2 supply energy to a main or working motor '3 which has a shunt fieldmagnet. winding 4. A starting resistor 5,

- which is in series with the armature'of the motor 3, is controlled by a drum controller 6 which is actuated by a ilot motor 7. The motor 7 is connected to tiie controller 6 by a reduction-gear mechanism. 8.

The circuit of the main motor 3 is controlled by an electromagnetic'ally operable line switch 9. The circuits for controlling the pilot motor and the line switch are coritrolled by manually operable switches 11 and 12, preferably of the push-button type. The functions of the push-button switches lldand 12 are indicated by appropriate legen s.

To start the main motor, the push-button switch 11 is actuated to complete a circuit that extends from line conductor 1, through push-button switch 11, resistor 14 and pilot motor 7 to line conductor 2. The pilot motor 7 actuates the controller 6 in a clockwise direction, as viewed from the right in Fig. 1.

When the contact segment 15 engages a 'pair of coacting contact fingers, a circuit is contact segment 15, actuating coil 16 of switch 9, push-button switch 12 and overload relay 17 to line conductor 2.

The llne switch 9 is closed by the coil 16, and the circuit of the main motor, which is thus completed, extends from line conductor 1, through resistor 5, armature of motor 3. line switch 9 and actuating coil of overload relay 17 to line conductor 2. A switch 13 which is mechanically connected to the switch 9, completes a holding circuit for the coil 16. A contact segment 25 completes a circuit for a signal lamp 26 which indicates the closing of the line switch '9.

When a contact segment 18 engages its corresponding contact finger, a circuit for the pilot motor is completed from line conductor 1, through the contact segments 19 to 23, contact segment 18, resistor 1a and pilot motor 7, to line conductor 2. This circuit is maintained by the contact segment 18 throughout the operation. of the controller. and the push-button switch 11 may, accordingly, be released as soon as this circuit is completed. The contact segment 25 1S disngaged from its contact finger simultaneously with the engagement of the contact segment 18 by the corresponding contact finger, breaking the circuit of the signal lamp 26.

' The resistor is shunted gradually as the several contact segments to 23 successively engage the corresponding contact fingers. When the controller6 is actuated to such position that the contact segment '18 becomes disengaged from its coacting contact finger, the circuit of the pi] broken and the controller comes to rest in running position which coincides with itsinitial or oif position; A signal lamp 271 indicates the period during which the pilot motor 7 is in operation to effect the acceleration of the main motor. The main circuit of the pilot motor-7 is the stopping of the main l of themain motor circuit.

- system ditions, such, for example, as age or overload conditions.

. case, the coil 16 is desener'gized to permit'the. I line switch 9 to open. In case 'upon a system disclosed motor now operates at its normal speed, with the entire resistor 5 so ents 19 and 23. v

ig) stop the motor 3, it is only necessary to shunted by the contact actuate the push-button switch 12 to openof an overload opens-the ciropens the circuit of the motor. It is impossible, however,

to efi'ect the starting actuated through its position to complete the circuit of coil en the entire resistor 5 is in circuit with the motor armature.

Reference may now'be had to which a modification iflers from initial Fig. 2 in is illustrated. This the system shown in of the pilot motor is'controlled accordingly.

he system of this gure is an improvement in a copending a plication by James, Serial No.-121,382, filed September 21, 1916, and assigned to the Westinghouse Electric & Manufacturing ompany.

To start the motor, the push-button switch is actuated to com lete the circuit of the pilot motor 7. ThlS circuit extends. from line conductor 1 through interlock push-button switch 11, interlock motor 7 and coil of overload relay conductor 2. The circuit of actuating coil 32 of line switch 33'is completed by contact segment 15, in th scribed in connection switch 30, 31, pilot 17 to,line

.ment 18 comp etes acircuit to or motor is of the mainmotor un-Y .less the controller is e manner previously dewith the corresponding parts. The interlock 30 completes a holding ci rcuitfor the coil 32, and the push-button switch 11 ma be released and contact segr the ilot motor 7 in parallel relation to the push button.

During the initial operation of the pilot motor 7, the resistor 14 is shunted and the pilot motor, accordingly, operates at arela tively high speed until the resistor 14 is-inserted in circuit therewith by the opening of.

lnterlock 31. During t of the accelerating period, the' pilot motor slow speed in order operates at a relatively that the sections of the starting resistor 5 may be shunted at a rate consistent with safety.

The, controller comes to'restin itsillus trated or initial position when thecontact segment 18 is disengaged from the sponding contact finger. As in the systems previously described, the controller is actuate a single direction from its initial position through a complete cycle starting'of the'main motor and to return to its normal, in'active position.

It may occur that, during the acceleration of't e main motor, the line switch 33 is opened by reason of failure of voltage ofthe source of supply or because of the operation of relay 17 in case an excessive current traverses the motor circuit. Inasmuch as the circuit of the pilot motor is not affected by the conditions described above, -it'will be obvious that, in case of v pilot motor will operate to complete its cycle upon the return of normal-voltage conditlons.

responsive means for actuating said controller and having a resistor and means for short-circuiting saidresistor when said closing means is in an inoperative position.

2. The combination'with an electric motor and a controller therefor, of a switch for closing the circuit of said motor,.a switch mechanically connected thereto, and a pilot motor for actuating said controller and havinga resistor, said mechanically connected- 1,4oaess switch serving to short-circuit said resistor when sa'idclosing switch is open.

3. The combination with an electric motor and acontroller therefor, of, a switch for closing the circuit of said motor and having an actuating coil, a switch mechanically connected to said closing switch, a pilot motor.

for actuating said controller, and means comprising said mechanically connected switch for operating said 'pilot motor at hi h 1 speed when said'closing switch is open, said mechanically connected switch establishing a'holding .circuitfor said coil and controlwith .ing t c ling the operation of said. pilot motor at low speed when said closing switch is closed.

4. In a system of-control, the combination with a main motor, a controller for governing the acceleration of saidmain'motor, and

a pilot motor for operating said controller at different speeds, of means for operating said ilot motor at uniform low speed duracceleration, of said motor.

5. In a system of control, the combination pi ot motor for' operating the controller, of means governed by the circuit conditions of the main motor for operating the pilot motor at either one of two uniform speeds.

6. In a system of control, a main motor, a controller associated with the main motor, and ele'ctro-responsive means for automatically operating said controller first at high speed and then at low'speed "during .the o eration of main motor.

7. In a system of control, a controller, a' pilot motor for operating the controller, and having a resistor and means for shortcircuiting said resistor to vary the s eed'of the pilot motor in: accordance with ,t e con dition of the circuits passing through the controller. v

8. In a system of control, a ,controller, having a plurality of circuits ppssing there through, that-is operable in a single direction, a motor for operatin .s'aid controller, overning t e speedof sald, motor in accor ance with the condition of" and means for the circuits passing through the controller. 9."In a system of control, a ma n motor, a controller associated withthe mam motor,

.a pilot motor for o eratingthe controller,

5 by said controller for Y and means controlle operating the pilot motor at an increased speed when the main motor-is de-energized.

10. In a s stem. of control, a main motor a line switc for completing the. circuit oi said main motor, and a pilot motor. for gov- Y erningthe acceleration of said mainmotor,

of a resistor in series with said pilot motor and means for short-circuiting said resistor when said line: switch is dc-energized.

11. In a s stem o f 'control, amain motor ii for completing the circuit of a line switc eration of the motor, an

for operating the controller, of a'line switch' said main motor.

a inain motor, a controller for. govern- .in the acceleration of the motor, and a Operation of the starting and accelerating said "signal when the pilot motor is o position.-

for, of means res the main motor,-and means, controller and a pilot motor, the acceleration of themain motor, of a resistor in series .with the ilot motor and means, comprising an inter ock switch associated with the line switch, for short circuiting said resistor when the line switch-is deenergized. I

12. In a system of control, the combination with a mam motor, a controller operable ina single direction for overnin the accel- If an auxi lary motor for governing for completing the circuit 0 and means governed b governing t e speed 0 n accordance with the the main motor, said lineswitch for circuit conditions of 13. In a system of control, the combination with a main motor, a switch for closing the circuit of said mainmotor, a controller associated with the main motor, and a pilot motor for operating the controller, of means comprising a said auxiliary motor.

governed by said switch for preventing the pilot motor when the controller is operating under normal 'conditions, and means for controlling the speed of the pilot motor in accordance with the circuit conditions of the main motor.

14. In a system of control, the combination with a' main motor, a controller associated with the main motor, and a pilot motor for operating the controller, of means controlled by said controller for indicating the closing of the main motor circuit and for giving a crating.

15." The combination with an e ent speeds.

17. The combination with a dynamo-electric machine and a rotatable controller thereonsive to difi'erent operat. ing conditions 0 said machine for varying the speed of said controller.

18. The combination with a dynamo-electric machine and a rotatable controller therefor, of electro-responsive means for automatic'ally operatingsaidcontroller ata lower speed during machine operation than during inoperative periods of said machine. 19. The combination with a dynamo-elecectric motor and a controller therefor, of a switch' 1 15 ltions of said machine for driving said controlling means at difierlac tricmachine and movable controlling means therefor, of power means for operating said controlling means, and means responsive to .manually operable means for initially ener- 10 gizing said machine, and means for slgnalling when it is permissible to release said manual means.

In testimony whereof,I have hereunto'subscribed my name this 21st day of August 16 191 7.

V CHARLES H. HODGKINS. 

